qubit

noun

qu·​bit ˈkyü-bət 

plural qubits

: a unit of computing information that is represented by a state of an atom or elementary particle (such as the spin) and can store multiple values at once due to the principles of quantum mechanics

And the most basic truth of quantum mechanics dictates that you cannot measure a qubit without destroying the superposition. The register that said 1 and 0 will randomly collapse into 1 or 0.

—George Johnson

compare bit entry 3 sense 1

Examples of qubit in a Sentence

Recent Examples on the Web

So while a Haar-random unitary for a few qubits is straightforward, one taking 25 qubits into account would require well over a quadrillion data points. —Quanta Magazine, 28 Mar. 2025

Unlike classical computers that store data in bits that are either on or off, quantum computers operate with quantum qubits, or qubits, that can be in both states at the same time. —Jordan Novet, CNBC, 26 Mar. 2025

Unlike classical computers, which process data as binary bits (0s or 1s), quantum bits (qubits) can exist in multiple states simultaneously, enabling them to represent both 0s and 1s simultaneously. —Guy Diedrich, Forbes, 24 Mar. 2025

Topological quantum computing is a fundamentally different approach to building a qubit, one that in theory would be a much less fragile. —IEEE Spectrum, 19 Mar. 2025

Word History

Etymology

qu- (in quantum entry 2) + bit entry 4, probably formed with punning allusion to cubit

Note: According to the American physicist Benjamin Schumacher, in the acknowledgements to a paper ("Quantum coding," Physical Review A, vol. 51, issue 4 [April, 1995], p. 2747), "The term 'qubit' was coined in jest during one of the author's many intriguing and valuable conversations with W. K. Wootters, and became the initial impetus for this work."

First Known Use

1994, in the meaning defined above

Rhymes for qubit

• cubit